This invention relates to X-ray fluoroscopic tables and the like and has particular reference to such tables which are adapted to support a patient in position so that X-rays or other similar radiation may be directed through the patient to an image receptor which comprises a radiation-sensitive film for producing a visible image of the irradiated area of the patient.
In conventional X-ray systems the X-ray sensitive receptor or film is suitably mounted in a cassette which is supported on a tray, called a bucky tray, adapted to be slid into and out of a support called a bucky frame. The bucky frame is a conventional shallow boxlike device having an open top and a front opening through which the tray is inserted into the frame whereby X-rays entering the frame through the open top will impinge upon the film supported on the tray. The table has an X-ray transparent top upon which the patient reposes, and the bucky frame is located in the table beneath the top. Since it is undesirable to continually reposition a patient during a series of X-ray exposures, the bucky frame is movably mounted in the table so that it may be adjusted with respect to the patient in a direction longitudinally of the table.
The bucky (frame and tray) weighs over twenty pounds, and the cassette varies from one to eight pounds and may be as large as seventeen inches square. Therefore, considerable weight is involved when a bucky frame, tray and cassette are to be moved as a unit.
Movement of the bucky frame, and consequent adjustment of the position of the film, has been accomplished by attaching the ends of a cable to the frame and mounting the cable on pulleys so that, upon manual manipulation of a crank attached to one of the pulleys, the pulleys can be rotated with consequent movement of the cable and frame.
In a tilting table the bucky frame is counterbalanced so that the operator can position it easily regardless of the tilt position of the table. However, the counterweight can accomodate only one combination of cassette and bucky weights. Therefore, it was necessary to additionally provide a mechanical lock to immobilize the bucky in its adjusted position.
Other prior developments included the provision of a rack and pinion device for moving the bucky and a mechanical clamp for locking it in place. A still later development involved the use of an electric motor with push button operation to move the cable and an electromagnet for rendering a pulley immovable to lock the bucky in adjusted position.
To install a cassette, the operator will pull a tray out of a bucky frame to its maximum "out" position as determined by a mechanical retainer, place the cassette between two clamping bars, and manipulate a lever which sets the bars. The tray is then reinserted in the bucky frame. Since both hands are required to install the cassette, it is a cumbersome and awkward maneuver by the operator to activate and deactivate a separate bucky lock during the loading and unloading procedures. When an operator neglects to operate the lock the bucky may inadvertently move with consequent damage to the mechanism or disturbance of the patient.